feat: Elasticsearch vector database

Makefile

@@ -310,6 +310,25 @@ test-python-universal-cassandra-no-cloud-providers:
 	  not test_snowflake" \
 	sdk/python/tests
 
+ test-python-universal-elasticsearch-online:
+	PYTHONPATH='.' \
+		FULL_REPO_CONFIGS_MODULE=sdk.python.feast.infra.online_stores.contrib.elasticsearch_repo_configuration \
+		PYTEST_PLUGINS=sdk.python.tests.integration.feature_repos.universal.online_store.elasticsearch \
+		python -m pytest -n 8 --integration \
+ 			-k "not test_universal_cli and \
+ 				not test_go_feature_server and \
+ 				not test_feature_logging and \
+				not test_reorder_columns and \
+				not test_logged_features_validation and \
+				not test_lambda_materialization_consistency and \
+				not test_offline_write and \
+				not test_push_features_to_offline_store and \
+				not gcs_registry and \
+				not s3_registry and \
+ 				not test_universal_types and \
+				not test_snowflake" \
+ 			sdk/python/tests
+
 test-python-universal:
 	python -m pytest -n 8 --integration sdk/python/tests
 

docs/reference/alpha-vector-database.md

@@ -10,7 +10,7 @@ Below are supported vector databases and implemented features:
 | Vector Database | Retrieval | Indexing |
 |-----------------|-----------|----------|
 | Pgvector        | [x]       | [ ]      |
-| Elasticsearch   | [ ]       | [ ]      |
+| Elasticsearch   | [x]       | [x]      |
 | Milvus          | [ ]       | [ ]      |
 | Faiss           | [ ]       | [ ]      |
 

docs/reference/online-stores/elasticsearch.md

@@ -0,0 +1,125 @@
+# ElasticSearch online store (contrib)
+
+## Description
+
+The ElasticSearch online store provides support for materializing tabular feature values, as well as embedding feature vectors, into an ElasticSearch index for serving online features. \
+The embedding feature vectors are stored as dense vectors, and can be used for similarity search. More information on dense vectors can be found [here](https://www.elastic.co/guide/en/elasticsearch/reference/current/dense-vector.html).
+
+## Getting started
+In order to use this online store, you'll need to run `pip install 'feast[elasticsearch]'`. You can get started by then running `feast init -t elasticsearch`.
+
+## Example
+
+{% code title="feature_store.yaml" %}
+```yaml
+project: my_feature_repo
+registry: data/registry.db
+provider: local
+online_store:
+    type: elasticsearch
+    host: ES_HOST
+    port: ES_PORT
+    user: ES_USERNAME
+    password: ES_PASSWORD
+    vector_len: 512
+    write_batch_size: 1000
+```
+{% endcode %}
+
+The full set of configuration options is available in [ElasticsearchOnlineStoreConfig](https://rtd.feast.dev/en/master/#feast.infra.online_stores.contrib.elasticsearch.ElasticsearchOnlineStoreConfig).
+
+## Functionality Matrix
+
+
+|                                                           | Postgres |
+| :-------------------------------------------------------- | :------- |
+| write feature values to the online store                  | yes      |
+| read feature values from the online store                 | yes      |
+| update infrastructure (e.g. tables) in the online store   | yes      |
+| teardown infrastructure (e.g. tables) in the online store | yes      |
+| generate a plan of infrastructure changes                 | no       |
+| support for on-demand transforms                          | yes      |
+| readable by Python SDK                                    | yes      |
+| readable by Java                                          | no       |
+| readable by Go                                            | no       |
+| support for entityless feature views                      | yes      |
+| support for concurrent writing to the same key            | no       |
+| support for ttl (time to live) at retrieval               | no       |
+| support for deleting expired data                         | no       |
+| collocated by feature view                                | yes      |
+| collocated by feature service                             | no       |
+| collocated by entity key                                  | no       |
+
+To compare this set of functionality against other online stores, please see the full [functionality matrix](overview.md#functionality-matrix).
+
+## Retrieving online document vectors
+
+The ElasticSearch online store supports retrieving document vectors for a given list of entity keys. The document vectors are returned as a dictionary where the key is the entity key and the value is the document vector. The document vector is a dense vector of floats.
+
+{% code title="python" %}
+```python
+from feast import FeatureStore
+
+feature_store = FeatureStore(repo_path="feature_store.yaml")
+
+query_vector = [1.0, 2.0, 3.0, 4.0, 5.0]
+top_k = 5
+
+# Retrieve the top k closest features to the query vector
+
+feature_values = feature_store.retrieve_online_documents(
+    feature="my_feature",
+    query=query_vector,
+    top_k=top_k
+)
+```
+{% endcode %}
+
+## Indexing
+Currently, the indexing mapping in the ElasticSearch online store is configured as:
+
+{% code title="indexing_mapping" %}
+```json
+"properties": {
+    "entity_key": {"type": "binary"},
+    "feature_name": {"type": "keyword"},
+    "feature_value": {"type": "binary"},
+    "timestamp": {"type": "date"},
+    "created_ts": {"type": "date"},
+    "vector_value": {
+        "type": "dense_vector",
+        "dims": config.online_store.vector_len,
+        "index": "true",
+        "similarity": config.online_store.similarity,
+    },
+}
+```
+{% endcode %}
+And the online_read API mapping is configured as:
+
+{% code title="online_read_mapping" %}
+```json
+"query": {
+    "bool": {
+        "must": [
+            {"terms": {"entity_key": entity_keys}},
+            {"terms": {"feature_name": requested_features}},
+        ]
+    }
+},
+```
+{% endcode %}
+
+And the similarity search API mapping is configured as:
+
+{% code title="similarity_search_mapping" %}
+```json
+{
+    "field": "vector_value",
+    "query_vector": embedding_vector,
+    "k": top_k,
+}
+```
+{% endcode %}
+
+These APIs are subject to change in future versions of Feast to improve performance and usability.

sdk/python/feast/feature_store.py

@@ -1886,7 +1886,7 @@ def retrieve_online_documents(
         feature: str,
         query: Union[str, List[float]],
         top_k: int,
-        distance_metric: str,
+        distance_metric: Optional[str] = None,
     ) -> OnlineResponse:
         """
         Retrieves the top k closest document features. Note, embeddings are a subset of features.
@@ -1911,7 +1911,7 @@ def _retrieve_online_documents(
         feature: str,
         query: Union[str, List[float]],
         top_k: int,
-        distance_metric: str = "L2",
+        distance_metric: Optional[str] = None,
     ):
         if isinstance(query, str):
             raise ValueError(
@@ -2209,7 +2209,7 @@ def _retrieve_from_online_store(
         requested_feature: str,
         query: List[float],
         top_k: int,
-        distance_metric: str,
+        distance_metric: Optional[str],
     ) -> List[Tuple[Timestamp, "FieldStatus.ValueType", Value, Value, Value]]:
         """
         Search and return document features from the online document store.